Treatment of refractory materials.



' E. WEINTRAUB.

TREATMENT or REFRACTORY MATERIALS.

APPLICATION FILED 13110.4, 1906. 997,879.

Patented July 11,1911.

Witnesses :f

v Inventor: E zechiel Wei raub,,

witt

UNITED STATES PATENT OFFICE nzncnmnwnm'rmnn, or scnnNnc'rAnY, NEW YORK, AssIeNoR 'ro GENERAL ELECTRIC 'COMIANY, A CORPORATION or NEW YO K.

To all whom it may concern.-

Be it known that I, EzncHraL WEINTRAUB, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, haveinvented certain new and useful Improvements in Treatment of Refractory Materials, of which the following is a specification.

' to heat a mixture of magnesium with an excess of boric anhydrid. This reaction is accompanied by the production of magnesium borate and by the formation of other'compounds. The resultant product, therefore, contains a relatively high percentage of material other than boron. The usual washing with water and hydrochloric acid decreases the percentage of impurity, but so far as I am aware, has never yielded a product which i could, in the sense,be termed pure pearance-and in boron. I have found, however, that this impure product can be greatlyimproved by what may be termed fractional decantation, 00 in grinding withwater or hydrochloric acid. and then decanting off the top of the liquid before complete precipitation has occurred; 1 I have found that boron has a greater specific gravity than the impurities suc 33 magnesium borid. By repeating thistreatment, I can reduce the proportion ofimpurities by several per cent., and in fact, secure. a resultant product quite dlfi'erentam ap properties from that hereto-1;

foreobtained.

To secure conductive boron fromthema' not of the reaction after due purification, I

ma compress theimpure boronQahove described into the form of a or-rod, say

centimeterslong and five Specification of Letters Patent.

Application filed December 4, 1906. Serial No.

the product 7 IRIEA'J!IMIIIirNT OF REFRACTORY MATERIALS.

Patented July 11, 1911. 346,253.

cross-section. This stick is then highly heated 1n a vacuum to dissociate and drive ofl" various of the impurities. For this heatlng treatment I may conveniently utiiizethe vacuum furnace described in United States patent to Arsem, No. 785,535, March 21; 1905." Thisfheat treatment dissociates any magnesium bor id which may be present and driy'es off the magnesium. Similarly, it dissoclates or volatilizes any boron'hydrid. In case any B 0 or any borate is present, that also passes off by direct volatilization. The

heat treatment may be continued for several hours at a temperature of say 1200 C. without any ,danger of contaminating the boron by- 'the'carbon of the resistance heater used in the furnace above mentioned. I have mentioned'the purification of the boron by this heating inthe vacuum, but I find that another very important change takes place,

and that the stick, which'beforetreatment was a non-conductor, becomes a relatively :good conductor of electricity. This surprismg result .is of great commercial importance, for the boron thus produced israd'ically different from that of the prior art as described in textbooks and technical-literature. I do not wish to be limited to any particular theory for. the conversion ofthis stick from a non-conductiveto a conductive condition, but such is the fact. The next step in 'my process consists in melting down this con ductive boron by heating it as anode in a vacuum arc. The apparatus for carrying out this step is illustrated in the drawing forming part of this Specification, and is herelnafter described in detail.

A hermetically sealed envelop lof-glass is provided at its bottom with a cup-shaped depression 2 capable of holding a suitable quantity of mercury for use as the cathode of a mercury arc. Suitable lead-wires 3 pass through the glass envelop and serve as means for connecting the mercury to a source of energy. A small tube 2 leads out of this .Jcup-shaped depression or cathode chamber 2 into a well 5 which servesas a receptacle into which mercury. may be drawn to lower the surface of the mercury cathode as ooterial above described or from the raw prod-;

casion may require. A suitable stop cock 6 is provided for controlling the flow of mercury into this well. A bottomless cup 7 of alumina is secured the mercury chamber and projects above the surface of the mercury and thereby prevents wandering of the cathode s ot over against the side of the glass enve 0p where. it might do damage by excessive heating. The upper end of the glass envelop is connected by a tube9 with a good vacuum pump, and this tube also communicates through suitable valves with a source of hydrogen 10 or other gas, whereby this gas may be admittedto the are chamber after the latter has been exhausted. A pressure gage 11 serves to indicate the state of the vacuum within the chamber and a small funnel 12 furnishes a ready means for "the introduction of mercury through tube 9 into the main chamber of the furnace. From the top of the furnace chamber 1 depends a rod or wire 13 surrounded. by a protective sleeve 14 and supportin at its lower end a carbon tube or sleeve wit in the end of which is secured one end of a] stick or rod 15 of the material to be treated or melted.

To start the apparatus into operation,

.exhaust the main chamber 1 and the mercury well 5 by means of the vacuum pump, and I then introduce suflicient mercury through funnel 12 to raise. the level in the alumina cup 7 until contact is made'with; the lower end,of the stick 15 to be treated. I next introduce a small quantity of gas inert with respect to the material to be treated, as' I have 'found that this addition concentrates the are on the lower end of the material under treatment and prevents the tendency which the arc would othervwise have of runnin to the lead-wire '13,

thisbeing particular y the case if the ma-' terial is of lower conductivity than the lead wire. Various gases; may be introduced to produce this concentration of the arc, and in general I consider that the-effect is due to the increased resistance offered to the passage of the am through the aseous medium of the envelop, by virtue 0 which the arc takes the shortest path to the anode and is thereby concentrated on the end thereof.

'If the stick under treatment consists of boronI may use hydrogen as the gas; and although the quantity may vary considerably, I prefer to use hydrogen at a pressure [of from two and a half to fifteen centimeters of mercury.

To start the are between the mercury cathode andthe solid anode 15, I open the :55

stop cock 6 and allow a small quantity of the cat ode mercury toflow through into the well 5 and thereby lower the level of the mercury in cup 7. This reduces an arc WlllCh can be drawn out to t a proper length by further subtraction of themercury. from the. cathode.

The heatin action of the-mercury arc is so intense an so concentrated that it fuses down the end of the stick into a head or globule, and I am thereby enabled to obtreatment furnishes an easy means for treating boron.

Pure conductive boron, as above described, may be used for a variety of purposes, and may be shaped into rods or glow bodies for use 1n incandescent lamps and furnaces.

fused globule produced in the vacuum arc, and then compressing the powderv so formed into rods of suitable size and shape, either with or without the use of binding material. I may use no binding material whatever, as I from any ingredients which might possibly lower the operating temperature. In case a binding material is used I prefer to employ one, such as paraflin, having the propbon in the residue, or at least one leaving so little carbon that the pro erties of the boron conductor are not sensib y affected thereby.

Dther methods may-be used for worln'ng the boron into rods or glow bodies'after the boron is in a pure condition. For instance, 'I- may use the process invented by W. D. Coolidge, disclosed in his application No. 316,006,'filed May 9, 1906, which consists in rubbing the finely divided refractory material into a warm and plastic amalgam conof cadmium and mercury. The boronmay weight or, in fact, until the amalgam is completely impregnated. :The material so produced is extruded warm through a die and is then heated by current in a vacuum, to drive out. the cadmium and mercury and leave a coherent conductor of the refractory material. Such a process is not only apphcable toslender wires, but is also applicable to rods or glow bodies of very considerable cross-section.

In a d'visional 401,811, ed November 12, 1907, claims are made on the apparatus'herein disclosed. In another divisional application, Serial No. 524,948, filed Oct. 27, 1909, claims are made on a rocesswherein this apparatus can be used in the treatment of refractory material.

In another divisional application, Serial No.

boron I have produced as.

concentration of the are on the anode under 1 am thereby enabled to keep the conductor free' erty of volatilizing out without leaving car taining approximately equal partsby weight application, Serial No.3

This may be effected by up the be added to the extent of several per cent. by v '585,391, filed October 5, 1910, claims .are

made on boron as an article of manufacture. What I claim as new and deslreto secure by Letters Patent of the United States, is,"

1. In the production of boron, the method which consists'in reducing boric anhydrid with magnesium, purifying the resultant product by Washing, grinding the-material thus obtained with a liquid and. decanting I impure boron in a vacuum to dissociate and drive ofl impurities therefrom.

4. The processwhich consists in treating impure boron in a vacuum to drive ofl' impurities and render said boron conductive.

5. The process which consists in heating impure boron until impurities are dissociated and driven-therefrom and said-boron becomes conductive for electricity. 6. The process which consists in renderment, mounting said boronas a'nodein an arc and fusing I pact body.

7. The process which consists-in heating conductive boronas anode in a mercury vapor arc to produce changes therein.

8. The process which consists in compressing impure boron into a stick, heating in a vacuum to dissociate and drive 011' impurities and render said boron conductive, and heating as anode 1n a mercury vapor arc to fuse said boron.

9. Theprocess which consists in producn c v 0 mg conductlve boron, and fusing said boron into a compact body.

The process of making pure boron mg impure boron conductive by heat treatdown said boron into a com-' which consists in heating impure boron in an inert environment until the impurities are driven ofl.

11. The process of making boron which consists in heating boron compounds in an inert environment until boron is produced therefrom.

12. The method which consists in purifying impure boron by heating it to high temperature in a mercuryarc. I

13. The method which. consists in purifying and fusing impure boron by heating it as anode for a mercuryarc in hydrogen.

14. The process of making fused boron, which consists in heating impure boron in a vacuum to drive off impurities and heating as anode for a mercury arc in hydrogen until said boron is fused;

15. The process which consists in mounting a body of conductive boron as anode in a'hermetically sealed chamber, and producing an arc thereto in an atmosphere of inert gas to'fuse said boron body.

16. The method which consists in reducing boric anhydrid with magnesium, purifying the resultant mixture by washing,

separating from said mixture the impure boron, pressing this boron into a rod and heating in a vacuum furnace to distil im-v purities and render said boron conductive, and then fusing said boron in\a mercury vapor furnace.- g v V 17. The method which consists in the production of impure boron, heatin said material in a vacuum to render it con uctive, and

heating to a higher temperature as anode in an arc.

18. The method which consists heating impure boron to render it conductive, and heating to a high temperature to .purlfy.

In witness whereof, Irhave hereunto set my hand this 3rd day of December,- 1906.

WEINTRAUTB.

' Witnesses: 1

BENJAMIN B. HULL, HELEN Onronn. 

